[quicwg/base-drafts] Does minimal encoding apply to extensions? (#3402)

Dmitri Tikhonov <notifications@github.com> Thu, 30 January 2020 15:17 UTC

Return-Path: <noreply@github.com>
X-Original-To: quic-issues@ietfa.amsl.com
Delivered-To: quic-issues@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id D2C38120168 for <quic-issues@ietfa.amsl.com>; Thu, 30 Jan 2020 07:17:52 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -7.999
X-Spam-Level:
X-Spam-Status: No, score=-7.999 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HTML_IMAGE_ONLY_32=0.001, HTML_MESSAGE=0.001, MAILING_LIST_MULTI=-1, RCVD_IN_DNSWL_HI=-5, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=github.com
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 6Cgu_KcrH9T4 for <quic-issues@ietfa.amsl.com>; Thu, 30 Jan 2020 07:17:50 -0800 (PST)
Received: from out-20.smtp.github.com (out-20.smtp.github.com [192.30.252.203]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id B8761120145 for <quic-issues@ietf.org>; Thu, 30 Jan 2020 07:17:50 -0800 (PST)
Date: Thu, 30 Jan 2020 07:17:49 -0800
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=github.com; s=pf2014; t=1580397469; bh=Nvs+WqGpk5P/NrYX3QAfZZTgfW7Cno1SICpZT+d8Hv8=; h=Date:From:Reply-To:To:Cc:Subject:List-ID:List-Archive:List-Post: List-Unsubscribe:From; b=QAuxeWBaDZOoAdyveESqp29tUi9rIYpivjj8Ht/+WkuEndeB2cQSGpoOUNK+tnqx0 7VGtd3acfwR8MamHJKsKS3B/6U/2/uWHkNTqssSy6zm2CUspKOLqOfeo+NcIkltKM2 j7rGCU1zO96l4v2oYb8PcCreUPTb4GY7MCnr+R5w=
From: Dmitri Tikhonov <notifications@github.com>
Reply-To: quicwg/base-drafts <reply+AFTOJKYGFR3X72OJ67TIRHV4IATB3EVBNHHCCO53EY@reply.github.com>
To: quicwg/base-drafts <base-drafts@noreply.github.com>
Cc: Subscribed <subscribed@noreply.github.com>
Message-ID: <quicwg/base-drafts/issues/3402@github.com>
Subject: [quicwg/base-drafts] Does minimal encoding apply to extensions? (#3402)
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="--==_mimepart_5e32f39d8fe12_207c3fd16c2cd9681725f4"; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: list
X-GitHub-Sender: dtikhonov
X-GitHub-Recipient: quic-issues
X-GitHub-Reason: subscribed
X-Auto-Response-Suppress: All
X-GitHub-Recipient-Address: quic-issues@ietf.org
Archived-At: <https://mailarchive.ietf.org/arch/msg/quic-issues/zlHRCKJmvAELE7n70gp9jAE0K3k>
X-BeenThere: quic-issues@ietf.org
X-Mailman-Version: 2.1.29
List-Id: Notification list for GitHub issues related to the QUIC WG <quic-issues.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/quic-issues>, <mailto:quic-issues-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/quic-issues/>
List-Post: <mailto:quic-issues@ietf.org>
List-Help: <mailto:quic-issues-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/quic-issues>, <mailto:quic-issues-request@ietf.org?subject=subscribe>
X-List-Received-Date: Thu, 30 Jan 2020 15:17:53 -0000

[Section 12.4 of the Transport Draft](draft-ietf-quic-transport-25#section-12.4) restricts frame type varint encoding:

```
   The Frame Type field uses a variable length integer encoding (see
   Section 16) with one exception.  To ensure simple and efficient
   implementations of frame parsing, a frame type MUST use the shortest
   possible encoding.  Though a two-, four- or eight-byte encoding of
   the frame types defined in this document is possible, the Frame Type
   field for these frames is encoded on a single byte.  For instance,
   though 0x4001 is a legitimate two-byte encoding for a variable-length
   integer with a value of 1, PING frames are always encoded as a single
   byte with the value 0x01.  An endpoint MAY treat the receipt of a
   frame type that uses a longer encoding than necessary as a connection
   error of type PROTOCOL_VIOLATION.
```

The relevant sentence is:

> Though a two-, four- or eight-byte encoding of the frame types defined in this document is possible, the Frame Type field for these frames is encoded on a single byte.

This means that the restriction may not apply to frames defined by QUIC extensions (such as the `ACK_FREQUENCY` frame in the _Delayed Acks_ extension).  Must each extension spell out its own frame type encoding rules?

It would be easier to change the transport draft to extend the minimal encoding restriction to not-as-yet-specified frames as well.

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/quicwg/base-drafts/issues/3402